Document email_notifications block in model serving resources (#4910)

## Changes
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## Tests
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- [x] relevant change in `docs/` folder
- [x] has entry in `NEXT_CHANGELOG.md` file

Author: alexott

NEXT_CHANGELOG.md

@@ -10,6 +10,8 @@
 
 ### Documentation
 
+* Document `email_notifications` block in model serving resources ([#4910](https://github.com/databricks/terraform-provider-databricks/pull/4910))
+
 ### Exporter
 
 ### Internal Changes

docs/resources/model_serving.md

@@ -133,6 +133,7 @@ The following arguments are supported:
 * `route_optimized` - (Optional) A boolean enabling route optimization for the endpoint. *Note: only available for custom models.*
 * `budget_policy_id` - (Optiona) The Budget Policy ID set for this serving endpoint.
 * `description` - (Optional) The description of the model serving endpoint.
+* `email_notifications` - (Optional) A block with Email notification setting.
 
 ### served_entities Configuration Block
 
@@ -259,6 +260,11 @@ The following arguments are supported:
 * `inference_table_config` - (Optional) Block describing the configuration of usage tracking. Consists of the following attributes:
   * `enabled` - boolean flag specifying if usage tracking is enabled.
 
+### email_notifications Block
+
+* `on_update_failure` - (Optional) a list of email addresses to be notified when an endpoint fails to update its configuration or state.
+* `on_update_success` - (Optional) a list of email addresses to be notified when an endpoint successfully updates its configuration or state.
+
 ## Attribute Reference
 
 In addition to all the arguments above, the following attributes are exported:

docs/resources/model_serving_provisioned_throughput.md

@@ -41,6 +41,7 @@ The following arguments are supported:
 * `tags` - Tags to be attached to the serving endpoint and automatically propagated to billing logs.
 * `ai_gateway` - (Optional) A block with AI Gateway configuration for the serving endpoint. *Note: only external model endpoints are supported as of now.*
 * `budget_policy_id` - (Optiona) The Budget Policy ID set for this serving endpoint.
+* `email_notifications` - (Optional) A block with Email notification setting.
 
 ### served_entities Configuration Block
 
@@ -76,6 +77,11 @@ The following arguments are supported:
 * `inference_table_config` - (Optional) Block describing the configuration of usage tracking. Consists of the following attributes:
   * `enabled` - boolean flag specifying if usage tracking is enabled.
 
+### email_notifications Block
+
+* `on_update_failure` - (Optional) a list of email addresses to be notified when an endpoint fails to update its configuration or state.
+* `on_update_success` - (Optional) a list of email addresses to be notified when an endpoint successfully updates its configuration or state.
+
 ## Attribute Reference
 
 In addition to all the arguments above, the following attributes are exported: